Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: pergunta: diga a média dos tempos de competição para os 7 jigs
 ###Tabelas: CREATE TABLE spain (spain_id AUTO_INCREMENT PRIMARY KEY, Name VARCHAR, Pos. VARCHAR, Height VARCHAR, Weight VARCHAR, Date of birth VARCHAR, Club VARCHAR) CREATE TABLE average_chart (average_chart_id AUTO_INCREMENT PRIMARY KEY, Rank by average INT, Competition finish INT, Couple VARCHAR, Total INT, Number of dances INT, Average VARCHAR) CREATE TABLE parliamentary_elections (parliamentary_elections_id AUTO_INCREMENT PRIMARY KEY, Election INT, Number of PNC votes VARCHAR, Share of votes VARCHAR, Seats VARCHAR, Outcome of election VARCHAR) CREATE TABLE building_and_withdrawal_data (building_and_withdrawal_data_id AUTO_INCREMENT PRIMARY KEY, Number INT, Builder VARCHAR, Built VARCHAR, Rebuilt VARCHAR, Name as rebuilt VARCHAR, Scrapped/Sold VARCHAR) CREATE TABLE b (b_id AUTO_INCREMENT PRIMARY KEY, Player VARCHAR, No. VARCHAR, Nationality VARCHAR, Position VARCHAR, Years in Toronto VARCHAR, School/Club Team VARCHAR)  
SELECT Rank by average FROM average_chart WHERE Number of dances = 7